The significance of absent end-diastolic velocity in umbilical artery velocity waveforms

Impact on postoperative, neonatal and 2-year neurodevelopmental outcomes of UA-AREDF during and after fetal spina bifida repair

OBJECTIVE

Absent or reversed end-diastolic flow (AREDF) in the umbilical artery (UA) on Doppler is a known phenomenon during fetal interventions, such as fetal open spina bifida (OSB) repair. We aimed to evaluate the clinical importance of these Doppler findings by investigating the impact of UA-AREDF on postoperative, neonatal and 2-year neurodevelopmental outcomes.

METHODS

This was a prospective study of pregnancies undergoing fetal OSB repair at the Zurich Center for Fetal Diagnosis and Therapy between 2010 and 2019. The group with UA-AREDF during or immediately after the intervention was compared to the group with normal UA Doppler. Primary endpoint was the FIGO scores of cardiotocography (CTG) 1, 2 and 6 h postoperatively and on day 1 after surgery. Secondary endpoints were the neonatal parameters and 2-year neurodevelopmental outcome assessed using the Bayley Scales of Infant and Toddler Development, Third Edition.

RESULTS

Data of 130 patients were analyzed. None of the fetuses had UA-AREDF before OSB repair. Normal UA Doppler was observed in 107 (82%) patients and UA-AREDF was observed in 23 (18%) during or immediately after OSB surgery. UA-AREDF was more often observed after version of the fetus (P = 0.045). Seventeen (13%) cases had absent end-diastolic flow (UA-AEDF) and six (5%) cases had reversed end-diastolic flow (UA-REDF). UA-AREDF disappeared in all 23 cases within the first day after OSB surgery. One-third of all CTGs were restricted in oscillation after surgery, but no significant difference in CTG 1, 2 and 6 h postoperatively or on the first postoperative day was found between the UA-AREDF and normal-Doppler groups (P > 0.05). Gestational age at delivery, UA pH, 5-min Apgar score and birth weight were comparable between the two groups, and there was no difference in the 2-year neurodevelopmental outcome (P > 0.05). The neonatal and 2-year neurodevelopmental outcomes also did not differ significantly between the UA-REDF and UA-AEDF groups.

CONCLUSIONS

Postoperative CTG abnormalities occur and recover at a similar rate in fetuses with transitory UA-AREDF and those with normal Doppler during fetal OSB repair. UA-AREDF during fetal OSB repair did not negatively influence postnatal or 2-year neurodevelopmental outcomes. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

FIGO (international Federation of Gynecology and obstetrics) initiative on fetal growth: best practice advice for screening, diagnosis, and management of fetal growth restriction

Fetal growth restriction (FGR) is defined as the failure of the fetus to meet its growth potential due to a pathological factor, most commonly placental dysfunction. Worldwide, FGR is a leading cause of stillbirth, neonatal mortality, and short- and long-term morbidity. Ongoing advances in clinical care, especially in definitions, diagnosis, and management of FGR, require efforts to effectively translate these changes to the wide range of obstetric care providers. This article highlights agreements based on current research in the diagnosis and management of FGR, and the areas that need more research to provide further clarification of recommendations. The purpose of this article is to provide a comprehensive summary of available evidence along with practical recommendations concerning the care of pregnancies at risk of or complicated by FGR, with the overall goal to decrease the risk of stillbirth and neonatal mortality and morbidity associated with this condition. To achieve these goals, FIGO (the International Federation of Gynecology and Obstetrics) brought together international experts to review and summarize current knowledge of FGR. This summary is directed at multiple stakeholders, including healthcare providers, healthcare delivery organizations and providers, FIGO member societies, and professional organizations. Recognizing the variation in the resources and expertise available for the management of FGR in different countries or regions, this article attempts to take into consideration the unique aspects of antenatal care in low-resource settings (labelled “LRS” in the recommendations). This was achieved by collaboration with authors and FIGO member societies from low-resource settings such as India, Sub-Saharan Africa, the Middle East, and Latin America.

Early Diagnosis of Carotid Stenosis by Ultrasound Doppler Investigations: A Classification Method for the Hemodynamic Parameter

Pulsed Wave Doppler (PWD) is a traditional ultrasound technique used for the diagnosis of cardiovascular disease. The conventional diagnostic method is based on hemodynamic parameters obtained from the PW spectrum. However, it relies on the clinical experience of sonographers, and especially focusing on severe carotid stenosis. This paper proposes a classification method for the hemodynamic parameter using the RUSBoost algorithm. The proposed method improves the performance of RUSBoost by setting the empirical weight of each sample. The experimental results show that the proposed method reaches the accuracy of 90.1%, the sensitivity of 70%, and the specificity of 94%, which are 4%, 6%, and 2% higher than the original RUSBoost respectively. In addition, the proposed method is objective, since the empirical weights are computed based on Mahalanobis distance without any expert input. It can be used for the early detection of cardiovascular disease.

No. 197a-Fetal Health Surveillance: Antepartum Consensus Guideline

OBJECTIVE

This guideline provides new recommendations pertaining to the application and documentation of fetal surveillance in the antepartum period that will decrease the incidence of birth asphyxia while maintaining the lowest possible rate of obstetrical intervention. Pregnancies with and without risk factors for adverse perinatal outcomes are considered. This guideline presents an alternative classification system for antenatal fetal non-stress testing to what has been used previously. This guideline is intended for use by all health professionals who provide antepartum care in Canada.

OPTIONS

Consideration has been given to all methods of fetal surveillance currently available in Canada.

OUTCOMES

Short- and long-term outcomes that may indicate the presence of birth asphyxia were considered. The associated rates of operative and other labour interventions were also considered.

EVIDENCE

A comprehensive review of randomized controlled trials published between January 1996 and March 2007 was undertaken, and MEDLINE and the Cochrane Database were used to search the literature for all new studies on fetal surveillance antepartum. The level of evidence has been determined using the criteria and classifications of the Canadian Task Force on Preventive Health Care (Table 1).

SPONSOR

This consensus guideline was jointly developed by the Society of Obstetricians and Gynaecologists of Canada and the British Columbia Perinatal Health Program (formerly the British Columbia Reproductive Care Program or BCRCP) and was partly supported by an unrestricted educational grant from the British Columbia Perinatal Health Program. RECOMMENDATION 1: FETAL MOVEMENT COUNTING: RECOMMENDATION 2: NON-STRESS TEST: RECOMMENDATION 3: CONTRACTION STRESS TEST: RECOMMENDATION 4: BIOPHYSICAL PROFILE: RECOMMENDATION 5: UTERINE ARTERY DOPPLER: RECOMMENDATION 6: UMBILICAL ARTERY DOPPLER.

Fetal growth velocity and body proportion in the assessment of growth

Fetal growth restriction implies failure of a fetus to meet its growth potential and is associated with increased perinatal mortality and morbidity. Therefore, antenatal detection of fetal growth restriction is of major importance in an attempt to deliver improved clinical outcomes. The most commonly used approach towards screening for fetal growth restriction is by means of sonographic fetal weight estimation, to detect fetuses small for gestational age, defined by an estimated fetal weight <10th percentile for gestational age. However, the predictive accuracy of this approach is limited both by suboptimal detection rate (as it may overlook non-small-for-gestational-age growth-restricted fetuses) and by a high false-positive rate (as most small-for-gestational-age fetuses are not growth restricted). Here, we review 2 strategies that may improve the diagnostic accuracy of sonographic fetal biometry for fetal growth restriction. The first strategy involves serial ultrasound evaluations of fetal biometry. The information obtained through these serial assessments can be interpreted using several different approaches including fetal growth velocity, conditional percentiles, projection-based methods, and individualized growth assessment that can be viewed as mathematical techniques to quantify any decrease in estimated fetal weight percentile, a phenomenon that many care providers assess and monitor routinely in a qualitative manner. This strategy appears promising in high-risk pregnancies where it seems to improve the detection of growth-restricted fetuses at increased risk of adverse perinatal outcomes and, at the same time, decrease the risk of falsely diagnosing healthy constitutionally small-for-gestational-age fetuses as growth restricted. Further studies are needed to determine the utility of this strategy in low-risk pregnancies as well as to optimize its performance by determining the optimal timing and interval between exams. The second strategy refers to the use of fetal body proportions to classify fetuses as either symmetric or asymmetric using 1 of several ratios; these include the head circumference to abdominal circumference ratio, transverse cerebellar diameter to abdominal circumference ratio, and femur length to abdominal circumference ratio. Although these ratios are associated with small for gestational age at birth and with adverse perinatal outcomes, their predictive accuracy is too low for clinical practice. Furthermore, these associations become questionable when other, potentially more specific measures such as umbilical artery Doppler are being used. Furthermore, these ratios are of limited use in determining the etiology underlying fetal smallness. It is possible that the use of the 2 gestational-age-independent ratios (transverse cerebellar diameter to abdominal circumference and femur length to abdominal circumference) may have a role in the detection of mild-moderate fetal growth restriction in pregnancies without adequate dating. In addition, despite their limited predictive accuracy, these ratios may become abnormal early in the course of fetal growth restriction and may therefore identify pregnancies that may benefit from closer monitoring of fetal growth.

Maternal Serum Analytes as Predictors of Fetal Growth Restriction with Different Degrees of Placental Vascular Dysfunction

Abnormal levels of maternal serum analytes have been associated with fetal growth restriction (FGR) and preeclampsia secondary to placental vascular dysfunction. Accurately identifying the FGR fetuses at highest risk for adverse outcomes remains challenging. Placental function can be assessed by Doppler analysis of the maternal and fetal circulation. Although the combination of multiple abnormal maternal serum analytes and abnormal Doppler findings is strongly associated with adverse outcomes, the predictive value remains too low to be used as a screening test in a low-risk population. Stratification of cases based on the severity of Doppler abnormalities may improve predictive models.

Survey on the current trends in managing intrauterine growth restriction

OBJECTIVE

To provide a snapshot of the current trends in managing intrauterine growth restriction (IUGR) and to assess the agreement on the gestational age and the way of delivery in different clinical scenarios.

METHODS

A PubMed search was performed to identify all original articles on IUGR in the last 6 years. The most active 20 authors were selected as experts and were invited to respond to a survey on their preferred gestational age for elective delivery in several IUGR cases depending on Doppler measurements (including umbilical artery (UA), middle cerebral artery, cerebroplacental ratio, uterine artery and ductus venosus), biophysical profile and cardiotocography.

RESULTS

15 of the 20 selected experts agreed to participate in the survey, of which 3 failed to meet the deadline to complete the survey. Management of IUGR was relatively uniform for abnormal UA, uterine artery or cerebroplacental ratio. Although average gestational age at delivery reflected a clear progression with accepted markers of severity, discrepancies of up to 4 weeks were found for abnormal middle cerebral artery Doppler and absent end-diastolic velocity in the UA, and of up to 8 weeks for reverse end-diastolic velocity in the UA and abnormalities in the ductus venosus Doppler.

CONCLUSIONS

Management of IUGR is still far from being uniform among centers, with most controversy surrounding the management of early-onset IUGR. There is a need of prospective studies to address this issue.

Predicting pH at birth in pregnancies with abnormal pulsatility index and positive end-diastolic velocity in the umbilical artery

OBJECTIVES

To identify potential associations between fetal surveillance tests and acidosis at birth in pregnancies with abnormal but positive end-diastolic velocity in the umbilical artery.

METHODS

A prospective case-control study [group 1: pH < 7.2; group 2: pH ≥ 7.2] including 46 fetuses with abnormal but positive end-diastolic velocity in the umbilical artery was conducted between February 2007 and March 2009. Outcome variables were evaluated by univariate analysis and compared between the two groups. Clinically relevant and statistically significant variables were analyzed by logistic regression.

RESULTS

Abnormal nonstress test, presence of deceleration, and absent fetal breathing movements were statistically significant. Logistic regression analysis revealed that fetal heart rate (FHR) deceleration in the nonstress test is the only predictor of fetal acidosis at birth (p = 0.024; OR = 8.2; 95%CI: 1.2-52).

CONCLUSIONS

In fetuses with positive end-diastolic flow velocity, acute variables of the antenatal surveillance tests are correlated with acidosis at birth and FHR deceleration in the nonstress test is the only predictor of fetal acidosis.

Morphological and functional evaluation of normal and abnormal fetal growth by ultrasonography

Correction or estimation of gestational age is essential for the evaluation of fetal growth. When necessary, an appropriate fetal biometric parameter should be selected depending on fetal size. In the first trimester, crown-rump length (CRL) is appropriate, especially when the CRL is 20-40 mm. In the second trimester, biparietal diameter (BPD), head circumference (HC), and femur length (FL) are of equal predictability. Fetal weight estimation is still the basis of evaluation of fetal growth. The most predictable formula currently available includes the parameters BPD (or HC), abdominal circumference (AC), and FL. Serial measurements of AC are useful for diagnosis of intrauterine growth restriction (IUGR) and macrosomia. Quantitative evaluation of soft tissue deposition may be informative for macrosomia. Functional evaluation using Doppler velocimetry is essential in IUGR cases associated with uteroplacental insufficiency. Analysis of blood velocity waveforms of the umbilical and intracranial arteries, predominantly the middle cerebral artery, is widely performed. An increase in the pulsatility index (PI) or resistance index (RI) of the umbilical artery and/or a decrease in the PI or RI of the middle cerebral artery are highly predictable for fetal hypoxia and/or acidosis.

Dynamics of the septum primum in fetuses with intrauterine growth restriction

PURPOSE

To test the hypothesis that the linear displacement of the septum primum (SP) is lower in fetuses with intrauterine growth restriction (IUGR) than in fetuses with appropriate growth for gestational age (AGA).

METHODS

In a cross-sectional study, the ratio between the SP displacement and left atrial diameter (excursion index [EI]) was compared in 27 fetuses with IUGR (group 1), 24 fetuses with AGA of hypertensive mothers (group 2), and 35 controls (group 3). Flow through the atrioventricular (AV) valves and the umbilical artery resistance index (RI) were also compared.

RESULTS

Irrespective of gestational age, mean EI in group 1 (0.41 +/- 0.07) was significantly lower than in group 2 (0.48 +/- 0.07; p < 0.001) and than in group 3 (0.50 +/- 0.06; p < 0.001), with no significant differences between groups 2 and 3. In fetuses over 30 weeks of gestation of group 1, EI was lower (0.38 +/- 0.05) than in group 2 (0.49 +/- 0.07) and group 3 (0.51 +/- 0.06; p < 0.001). There was significant inverse correlation between EI and RI (r = 0.46; p < 0.01) and no correlation between EI and AV flow velocities.

CONCLUSIONS

SP mobility is reduced in fetuses over 30 weeks with IUGR compared with AGA fetuses. These findings may depend on alterations of left ventricular diastolic function and are correlated to the degree of placental insufficiency.

Doppler ultrasonography in uteroplacental insufficiency

Much of our understanding of uteroplacental insufficiency has been derived from animal research and the study of the pathology of human placental and uterine biopsies. These studies have shown how the placenta plays a major role in the development of normal pregnancy and how placental dysfunction is generally caused by factors interfering with the normal growth of the uteroplacental and/or fetoplacental circulations. These abnormalities lead to a deficient supply of oxygen and nutrients to the fetus and to several complications of pregnancy such as gestational hypertension, preeclampsia and intrauterine growth retardation (IUGR).

Predicting pH at Birth in Absent or Reversed End-Diastolic Velocity in the Umbilical Arteries

OBJECTIVE

To investigate arterial and venous blood flow in fetuses with absent or reversed end-diastolic flow in the umbilical arteries and to correlate the Doppler results with umbilical artery blood pH at birth to predict the probability of acidosis at birth.

METHODS

Ninety-one fetuses from singleton pregnancies without fetal malformations with a diagnosis of absent or reversed end-diastolic flow in the umbilical arteries were prospectively studied. On the day of delivery, Doppler velocimetry of the umbilical arteries, middle cerebral artery, and ductus venosus was performed and the results were correlated with umbilical artery pH at birth at the following cutoff levels: pH < 7.20, < 7.15, < 7.10, and < 7.05. The association between fetal arterial and venous Doppler velocimetry and acidosis was then individually analyzed by the chi(2) and Fisher exact tests. The ability of these tests to predict the probability of acidosis at birth was estimated using a logistic regression model.

RESULTS

There was a negative correlation between pH at birth and umbilical artery pulsatility index (r = -0.39; P < .001) and pulsatility index for veins in the ductus venosus (r = -0.63; P < .001). Assessment of the fetal arterial circulation (middle cerebral artery) showed no statistical correlation with pH at birth. Using logistic regression analysis, probability curves were constructed for pH values less than 7.20 (odds ratio [OR] 8.03), less than 7.15 (OR 11.92), less than 7.10 (OR 12.16), and less than 7.05 (OR 8.20).

CONCLUSION

The pulsatility index for veins of the ductus venosus was related to pH at birth, demonstrating that the higher the ductus venosus pulsatility index for veins, the lower the pH at birth. Once the pulsatility index for veins in the ductus venosus is known, the probability of acidosis at birth can be estimated.

Absent or reverse end-diastolic flow in the umbilical artery: intellectual development at school age

OBJECTIVE

This study was designed to establish whether, in growth-retarded fetuses, absent or reverse end-diastolic (ARED) flow velocity in the umbilical artery can be predictive of an increased incidence of long-term neurological and intellectual impairment.

STUDY DESIGN

A total of 14 children with intra-uterine growth retardation (IUGR) and ARED flow in the umbilical artery and 11 children without this velocimetric pattern were examined by pediatric neuropsychiatrists at a median age of 8.7 years to evaluate and compare their neurological and intellectual development.

RESULTS

The incidence of major neurological sequelae was higher in the children with ARED velocity in the umbilical artery (21%) than in those without this velocimetric pattern (9%), as was the incidence of mild neurological sequelae (35% versus 27%). No differences in mean intelligence quotient (IQ) as evaluated by mean of Intelligence Scale for Children-Revised (WISC-R) scale were found between the two groups of children at school age.

CONCLUSIONS

Our data demonstrate that Doppler velocimetry in the umbilical artery is a reliable predictor for neurological sequelae when ARED flow is present but cannot be considered a good predictor of intellectual performance at school.

Doppler application in the delivery timing of the preterm growth-restricted fetus: another step in the right direction

This article provides an opinion on a study of relationships between umbilical artery (UA) Doppler, ductus venosus (DV) Doppler, fetal heart rate variation, and perinatal outcome in preterm, intrauterine growth-restricted (IUGR) fetuses published in the same issue of this journal by Bilardo and coworkers. Recent evidence on venous Doppler surveillance in preterm IUGR fetuses was also reviewed and discussed in the context of the study with a special emphasis on delivery timing. A search was conducted through MEDLINE and eight articles with similar inclusion criteria and reporting format of outcomes were identified. Numbers for perinatal mortality, intraventricular hemorrhage, respiratory distress syndrome, bronchopulmonary dysplasia and necrotizing enterocolitis (NEC) were extracted for cases where Doppler status was recorded in an identical format. Proportional distribution of outcomes was compared for fetuses with normal DV Doppler velocimetry, absent or reversed UA end-diastolic velocity (UA A/REDV), elevated DV Doppler index (abnormal DV) and absence or reversal of atrial velocity in the DV (DV-RAV). A total of 320 fetuses with normal and 202 with elevated DV Doppler indices were extracted. Of these fetuses, 101 with UA A/REDV only and 34 with DV-RAV were identified. Perinatal mortality was 5.6% (16/282) with normal DV, 11.9% (12/101) with UA A/REDV, 38.8% (64/165) with abnormal DV and 41.2% (7/17) with DV-RAV. With the exception of NEC, all complications were significantly more frequent with abnormal DV. With normal venous Doppler neonatal deaths account for most of the perinatal mortality, while with abnormal DV stillbirths and neonatal mortality are similar contributors to the significantly increased perinatal mortality. In conclusion, UA Doppler is a placental function test that provides important diagnostic and prognostic information in preterm IUGR. DV Doppler effectively identifies those preterm IUGR fetuses that are at high risk for adverse outcome (particularly stillbirth) at least 1 week before delivery, independent of the UA waveform. Relationships between perinatal outcome, arterial and venous Doppler status and gestational age require ongoing observational research effort. Randomized management trials are necessary to verify that delivery timing based on venous Doppler will impact on outcome in preterm IUGR.

Doppler flow velocity to measure the redistribution of fetal cardiac output in fetal stress

The pathophysiologic continuum of poor uterine and placental blood flow associated with fetal growth restriction has to be considered the major cause of poor birth outcomes. The main attention in this context is drawn to the possibilities of an early diagnosis of imminent fetal compromise prior to and under delivery. With regard to this, the detection of a reduced fetal oxygen saturation (fetal stress) plays a crucial role, whereas an acute incident causing fetal hypoxemia has to be differentiated from a chronic hypoxemic condition. An acute hypoxemia under delivery is best detected by cardiotocography. Due to its infrequent and unpredictable occurrence, an acute antenatal hypoxemia usually escapes common surveillance methods. Fetal biometry and pulsed Doppler sonography are to be considered the most suitable methods to diagnose chronic hypoxemic fetal conditions. The interrogation of a combination of peripheral and central vessels allow the sonologist to characterize the extend of a progressively deteriorating oxygen supply. However, this correlation is not yet completely understood. Therefore, clinical consequences still have to be drawn by cardiotocographic findings indicating a global cardiac decompensation.

Middle cerebral artery to umbilical artery resistance index ratio in the prediction of neonatal outcome

OBJECTIVE

The objectives of this study were to evaluate the usefulness of the middle cerebral artery to umbilical artery resistance index ratio (C/U ratio) as a predictor of adverse perinatal outcome, and to show that the absence of fetal umbilical artery end-diastolic velocity (AEDV) in SGA fetuses is associated with high morbidity and mortality.

METHOD

In this prospective study, color Doppler flow imaging was used for the estimation of the C/U ratio in fetuses that were small for their gestational age, in 70 singleton pregnancies between 29 and 42 weeks of gestation. The subjects were categorized into two groups, with Group A consisting of 35 small for gestational age (SGA) fetuses with a normal C/U ratio (1.05 or higher), and Group B comprising 35 SGA fetuses with an abnormal C/U ratio (below 1.05).

RESULT

The mean C/U ratio values for birth weight and gestational age were higher in group A than in group B. Fetuses born to mothers in group B stayed longer in the neonatal special care unit (NSCU), whereas the period from ultrasound examination to delivery was higher in the cases in group A. A higher percentage of mothers with an abnormal C/U ratio underwent cesarean section. Fetuses with an absent end-diastolic velocity of the umbilical artery had a higher morbidity. Three stillbirths occurred in fetuses with an absent end-diastolic velocity of the umbilical artery.

CONCLUSION

Our results suggest that the C/U ratio is a good predictor of neonatal outcome, and could be used to identify fetuses at risk of morbidity and mortality. Fetal umbilical artery AEDV with intrauterine growth restriction is associated with high perinatal morbidity and mortality.

Volumetric flow in the umbilical artery: normative data

OBJECTIVE

Provide normative data for the volumetric blood flow (cc/min and cc/min/kg) in the umbilical artery.

METHODS

Flow was determined from an umbilical artery in 252 normal obstetrical patients from 18-40 weeks' gestation utilizing pulsed Doppler and color flow Doppler with an angle of insonation of 30-60 degrees. Simultaneous velocimetry studies (S/D ratio, resistance and pulsatility indices), fetal biometry, and an anatomic survey were obtained to further define the normal population.

RESULTS

There was a steady increase in the flow (cc/min) in the umbilical artery as pregnancy progressed. Flow/kg showed a steady decline as fetal weight increased. Umbilical artery diameter increased until reaching a plateau at 32-34 weeks. Velocimetric results were consistent with known data.

CONCLUSIONS

Volumetric blood flow in the umbilical artery can be determined with relative ease and normative data from 18-40 weeks is presented for the first time.

Prenatal sonographic detection of nasopharyngeal teratoma

We present the case of a 34-year-old pregnant woman who had an elevated maternal serum alpha-fetoprotein level and sonographic findings of a semisolid mass protruding from the fetus's oral cavity. The large, heterogeneous mass filled the oropharynx and nasopharynx. Abnormal Doppler waveforms were detected in the umbilical artery of the fetus, who died in utero. Postmortem examination revealed a nasopharyngeal teratoma.

The Doppler cerebroplacental ratio and perinatal outcome in intrauterine growth restriction

OBJECTIVE

Our purpose was to determine whether the Doppler cerebroplacental ratio predicts perinatal outcome in fetuses at risk for intrauterine growth restriction.

STUDY DESIGN

The middle cerebral and umbilical artery pulsatility index values were measured in 203 fetuses at risk for intrauterine growth restriction, of which 123 were delivered <3 weeks after the last Doppler examination. Perinatal outcome was categorized as (1) birth weight <10th percentile, (2) birth weight <5th percentile, (3) perinatal complications (meconium-stained fluid, cesarean section for fetal distress, 5-minute Apgar score <7, perinatal death, neonatal intensive care unit stay >24 hours, hypoglycemia, or polycythemia), (4) birth weight <10th percentile plus complications, and (5) birth weight <5th percentile plus complications. The cerebroplacental ratio (middle cerebral artery pulsatility index divided by umbilical artery pul-satility index) values were expressed as multiples of the normal median. Receiver-operator characteristic curves (sensitivity vs false-positive rates) were plotted for the prediction of each category of perinatal outcome and the areas under the curves were determined. Stepwise logistic regression analyses were used to determine whether the cerebroplacental ratio improved outcome prediction over umbilical artery Doppler imaging alone.

RESULTS

There was a statistically significant increase in perinatal morbidity and mortality in cases with an abnormal cerebroplacental ratio. The areas under the receiver-operator curves characteristics for the prediction of perinatal outcome with use of the cerebroplacental ratio were statistically very significant. For birth weight <10th percentile we noted P <.001, with P <.0001 for each of the other 4 outcome categories. As shown by regression analyses, the cerebroplacental ratio appeared to improve the prediction of perinatal outcome compared with umbilical artery velocimetry alone. An interesting finding was that the cerebroplacental ratio did not appear to correlate significantly with outcome in fetuses at >34 weeks.

CONCLUSION

Doppler identification of the fetal "brain-sparing" effect strongly predicts outcome in fetuses at risk for intrauterine growth restriction. The brain-sparing effect predicted perinatal problems only in fetuses <34 weeks' gestation at the Doppler examination.

Using S/D Ratios to Predict Fetal Outcome

The systolic/diastolic (S/D) ratio is a measurement of the umbilical cord artery that compares the systolic with the diastolic flow and identifies the amount of resistance in the placental vasculature. This retrospective study made a direct comparison between the S/D ratios of third-trimester fetuses and their birth weights. Previous studies have reported fetuses with S/D ratios greater than 3.0, after 30 gestational weeks, to be at an increased risk for low birth weight. This study looked at outcomes of fetuses with S/D ratios greater than 3.0, and ratios less than 3.0. One hundred S/D ratios were obtained and divided into three categories: less than 2.0, between 2.0 and 3.0, and greater than 3.0. The collected data showed 35.5% of low-birth-weight neonates had S/D ratios greater than 3.0. Those patients with S/D ratios less than 2.0 had the largest percentage (37.5%) of neonates above the 50th percentile in weight, whereas ratios between 2.0 and 3.0 had the highest percentage (59.46%) of neonates between the 11th and 50th weight percentiles. The S/D ratio is easily obtained and provides important information in conjunction with fetal structural measurements when predicting the outcome of a fetus.

Does increased resistance on umbilical artery Doppler preclude a trial of labour?

OBJECTIVE

To determine whether patients with increased resistance on umbilical artery Doppler velocimetry could be safely allowed a trial of labour.

DESIGN

The Coombe Womens' Hospital is a university teaching hospital which takes tertiary referrals. All singleton pregnancies found to have increased resistance (>2 SD above the mean for gestational age) on umbilical artery Doppler ultrasound between 1993 and 1995 inclusively were identified from the ultrasound database and reviewed, retrospectively. Cases where the umbilical artery waveform reverted to normal or deteriorated to absent end diastolic flow on a subsequent scan were excluded. The 118 cases identified were divided into two groups, those that were delivered by elective caesarean section and those that laboured.

RESULTS

Forty-five patients were delivered by elective caesarean section and 73 were allowed to labour. In the group that laboured over 90% delivered vaginally and 9.8% were delivered by emergency caesarean section. Three babies had a cord pH less than 7.20 in the group that laboured. Two babies had an Apgar score of less than 7 at 5 min in the group that were delivered electively. There were no neonatal seizures or perinatal deaths in either of the two groups.

CONCLUSIONS

This study shows that patients with increased resistance on umbilical artery Doppler can be allowed a trial of labour without compromising the fetal outcome. We would suggest that consideration be given to induction of labour in selected patients as an alternative to elective section.

Neonatal nucleated red blood cell counts in small-for-gestational age fetuses with abnormal umbilical artery Doppler studies

OBJECTIVE

The presence of elevated nucleated red blood cell counts in neonatal blood has been associated with fetal hypoxia. We sought to determine whether small-for-gestational-age fetuses with abnormal umbilical artery Doppler velocity waveforms have elevated nucleated red blood cell counts.

STUDY DESIGN

Hospital charts of neonates with the discharge diagnosis of small for gestational age (birth weight < 10th percentile) who were delivered between October 1988 and June 1995 were reviewed for antepartum testing, delivery conditions, and neonatal outcome. We studied fetuses who had an umbilical artery systolic/diastolic ratio within 3 days of delivery and a complete blood cell count on the first day of life. Multiple gestations, anomalous fetuses, and infants of diabetic mothers were excluded. Statistical analysis included the Student t test, chi 2 analysis, analysis of variance, and simple and stepwise regression.

RESULTS

Fifty-two infants met the inclusion criteria. Those with absent or reversed end-diastolic velocity (n = 19) had significantly greater nucleated red blood cell counts than did those with end-diastolic velocity present (n = 33) (nucleated red blood cells/100 nucleated cells +/- SD: 135.5 +/- 138 vs 17.4 +/- 23.7, p < 0.0001). These infants exhibited significantly longer time intervals for clearance of nucleated red blood cells from their circulation (p < 0.0001). They also had lower birth weights (p < 0.05), lower initial platelet count (p = 0.0006), lower arterial cord blood pH (p < 0.05), higher cord blood base deficit (p < 0.05), and an increased likelihood of cesarean section for "fetal distress" (p < 0.05). Multivariate analysis demonstrated that absent or reversed end-diastolic velocity (p < 0.0001) and low birth weight (p < 0.0001) contributed to the elevation of the nucleated red blood cell count, whereas gestational age at delivery was not a significant contributor.

CONCLUSION

We observed significantly greater nucleated red blood cell counts and lower platelet counts in small-for-gestational-age fetuses with abnormal umbilical artery Doppler studies. This may suggest that antenatal thrombotic events lead to an increased placental impedance. Fetal response to this chronic condition may result in an increased nucleated red blood cell count.

An automated intelligent diagnostic system for the interpretation of umbilical artery Doppler velocimetry

The objective is to develop an automated intelligent diagnostic system for the interpretation of umbilical artery velocity waveforms. An ultrasound instrument with pulsed-wave Doppler is connected to a microcomputer by means of a frame grabber. After data acquisition, umbilical Doppler velocimetry is handled as a pattern recognition (feature extraction and classification) and decision-making problem. Automated image processing (enhancement, smoothing/ thresholding and edge detection) and analysis are used for feature extraction. Six waveform indices obtained by feature extraction are used as input layer to vector quantization which classifies waveforms into six groups. A clinical decision is assigned to each group by the medical expert. Our system is trained by 278 and 380 waveform images of 94 normal and 157 high risk pregnancies, respectively. The system was tested with 193 and 61 images of normal and risky pregnancies; it was demonstrated that sensitivity and specificity of the system are 54.1% and 80.3%, respectively.

Umbilical artery pulsatility index in early pregnancies with chromosome anomalies

OBJECTIVE

The aim of our study was to obtain measurements of the umbilical artery pulsatility index in pregnancies before invasive procedures for prenatal diagnosis, to investigate its potential prognostic value in predicting chromosomal abnormalities.

DESIGN

A prospective study.

PARTICIPANTS

Nine hundred and twenty-four consecutive women with singleton pregnancies between 10 and 18 weeks of gestation who underwent chorionic villus sampling (n = 385) or genetic amniocentesis (n = 539). All Doppler measurements were obtained by a single investigator before the invasive procedure. Pregnancies where structural malformations were detected by ultrasound were excluded.

RESULTS

Twenty-six fetuses with chromosomal anomaly, including 12 with trisomy 21, were diagnosed. Using the 90th centile in umbilical artery pulsatility index values as a cut-off for trisomy 21 the detection rate was 66.6%, with a specificity of 90.4% and a positive predictive value (defined as the proportion of unaffected individuals with positive results, l-specificity) of 8.8%. However, with this cut-off the false positive rate was 9.6%. All 19 chromosomally normal pregnancies in which a fetal loss occurred after the procedure had a normal umbilical artery pulsatility index before it was carried out.

CONCLUSIONS

These preliminary data suggest that trisomic fetuses have an abnormally increased umbilical artery pulsatility index in early pregnancy. Because the number of cases is too small to draw any firm conclusions, the use of a single measurement for screening purposes needs to be confirmed by further investigation and the clinical significance of reference curves of normal values in the detection of pathological conditions has still to be determined. The potential of umbilical artery pulsatility index as an additional parameter along with others previously established for Down's syndrome screening, such as nuchal oedema, needs to be explored further.

Fetal pH value determined by cordocentesis: an independent predictor of the development of antepartum fetal heart rate decelerations in growth retarded fetuses with absent end-diastolic velocity in umbilical artery

Objective of this study was to establish the relationship in growth retarded fetuses between acid-base status in fetal blood obtained by cordocentesis and time interval between blood sampling and occurrence of antepartum heart rate late decelerations. Eighteen growth retarded fetuses scheduled for cordocentesis were considered for this study. All fetuses were free from structural and chromosomal abnormalities, characterized by absent end diastolic velocity waveforms in umbilical artery and later delivered for the development of antepartum heart rate late decelerations. Regression analysis showed that the time interval between cordocentesis and delivery was significantly related to pO2 (r = 0.46; p < or = 0.05) and pH (r = 0.57; p < or = 0.01) delta values but not with pCO2 values. Stepwise multiple regression analysis demonstrated that the severity of fetal acidosis significantly and independently predicted the length of this time interval even after controlling for confounding variables such as pO2 values, gestational age, presence of hypertension, or umbilical vein pulsations. The knowledge of this relationship may be useful in the clinical management of growth retarded fetuses.

Umbilical artery Doppler velocimetry: clinical utility in high-risk pregnancies

An abnormal result of an umbilical artery Doppler study reflects the presence of placental vascular pathologic mechanisms and identifies pregnancies at increased risk for perinatal mortality. Recent reviews of the clinical utility of umbilical artery Doppler study have concluded that it should not be routinely used as a screening modality for the general obstetric population and have suggested that further research is required. However, metaanalysis of published peer-reviewed and randomized controlled trials indicates that its use in high-risk pregnancies is associated with a significant decrease in perinatal mortality without an increase in the rate of inappropriate obstetric intervention. This clinical opinion serves to underscore the relevance of umbilical artery Doppler velocimetry to clinical practice and to suggest that an abnormal result of an umbilical artery Doppler study should be added to the current list of indications for intensive fetal surveillance.

Use of cordocentesis in the management of preterm or growth-restricted fetuses with abnormal monitoring

The dilemma of when to deliver preterm or growth-restricted fetuses with abnormal monitoring is faced by all those treating such patients. Current noninvasive tests for fetal well-being have relatively high false-positive rates. Cordocentesis allows the clinician to directly analyze fetal blood and determine whether the fetus is truly in distress, is suffering from aneuploidy, or is plagued by infection. However, with improved neonatal care, otherwise normal infants of birth weight greater than 1500 gm have very low morbidity and mortality rates and any delay in delivery offered by cordocentesis is probably not justified. It is in the fetus whose estimated weight is below 1500 gm that cordocentesis should be used. If the results are normal, expectant management and the administration of corticosteroids will allow for pulmonary maturation and a more favorable outcome.

Early fetal circulation in pregnancies complicated by retroplacental hematoma

The objective of this study was to investigate the effects in early gestation of retroplacental hematomas on Doppler indices measured in different fetal vascular districts and to relate these changes, if any, to the volume of hematoma and pregnancy outcome. Thirty-eight pregnancies complicated by bleeding and ultrasonographic findings of retroplacental hematomas were considered for this study. Menstrual age ranged between 9 and 14 weeks. Blood flow velocity waveforms were measured in the umbilical artery, descending aorta, middle cerebral artery, and inferior vena cava. The pulsatility index in arterial vessels was calculated as well as the percentage reverse flow in the inferior vena cava. The values obtained were compared to previously constructed reference limits. No significant differences were found for any of the Doppler indices when the values obtained in pregnancies complicated by retroplacental hematomas were compared to the reference limits. Furthermore no significant relationships were found between the Doppler indices and either the size of hematoma or pregnancy outcome. In conclusion, retroplacental hematoma does not induce hemodynamic effects in the fetal circulation before 14 weeks, menstrual age. These data do not support the use of Doppler ultrasonography in early gestation for pregnancies complicated by bleeding and retroplacental hematomas.

Behavioural development and Doppler velocimetry in relation to perinatal outcome in small for dates fetuses

Twenty-two small for dates (SFD) fetuses and 96 fetuses from uncomplicated pregnancies were monitored on two occasions between 27 and 32 weeks and the second time between 33 and 36 weeks of gestation by studying the development of behavioural states (coincidence 1F and 2F; no coincidence) and umbilical artery Doppler waveform patterns (UA; Resistance Index, RI). Data were related to neurological outcome at 8 months after birth. The purpose of this study was to investigate if the development of behavioural state is disturbed in SFD fetuses and if SFD fetuses who needed to be delivered early and/or had abnormal neurological outcome showed different state development and RI than SFD fetuses delivered later in pregnancy or with normal neurological outcome. Finally, we studied if there was a relationship between state development and RI. At 27-32 weeks of gestation the percentage of coincidence 2F (C2F%) was lower and the percentage of coincidence 1F (C1F%) and no coincidence (NOC%) were higher in the SFD fetuses than in the control group. At 33-36 weeks C2F% was lower and NOC% was higher but not statistically different (P = 0.2 and P = 0.07, respectively). SFD fetuses who needed to be delivered early had poorer state development than SFD fetuses at lower risk and infants who were abnormal at 8 months of life showed a higher C1F% and lower C2F% at 27-32 weeks. There were significant correlations between RI on the one hand and NOC% (r = 0.62) and C2F% (r = -0.48) on the other hand at 27-32 weeks in the subgroup with abnormal neurological outcome. In conclusion, in SFD fetuses there are disturbances in the development of behavioural states as well in the distribution of the periods of coincidence (with a decrease in C2F% and an increase in C1F%). Poorest state development is present in SFD fetuses at highest risk and in this group there appears to be a significant relationship between the degree of utero-placental insufficiency (RI) and disturbances in behavioural development.

Growth deficient fetuses with absent or reversed umbilical artery end-diastolic flow are metabolically compromised

Controversy continues regarding the clinical relevance of absent or reversed umbilical artery blood flow during diastole. The purpose of this study was to characterize the blood gas and lactate measurements of growth deficient fetuses with absent (ADF) or reversed (RDF) umbilical artery (UA) diastolic flow. In a descriptive study from February 1988 through October 1991, 42 consecutive structurally and karyotypically normal growth deficient fetuses identified to have either ADF or RDF diastolic flow in the UA were studied. Heparinized blood specimens were obtained from them and the pH, PCO2, PO2 and lactate measured. Fourteen of these specimens were obtained from the umbilical vein by cordocentesis and 28 at the caesarean delivery of non-labouring patients. Statistical analyses were performed using Fisher's exact test, Student t-test and linear correlation. All measured parameters in fetuses with ADF or RDF undergoing cordocentesis were significantly abnormal compared to gestational age corrected norms. Both the mean venous and arterial pH of fetuses with RDF were significantly lower than that of fetuses with ADF. With few exceptions, preoperative maternal oxygenation failed to correct the fetal hypoxaemia associated with either ADF or RDF. In the setting of severe fetal growth deficiency secondary to uteroplacental dysfunction, ADF and RDF are clinically reliable indicators of fetal compromise as determined by the umbilical blood gases. RDF is associated with a greater impairment of placental gas exchange than ADF.

Absence of end-diastolic flow velocity in the umbilical artery: a review

The objective of this review was to find the clinical relevance of the absence of end-diastolic flow velocity in the umbilical artery. Search was conducted through MEDLINE using unabridged MEDLINE Knowledge Finder (Aries System Corp., North Andover, MA). All the manuscripts published in English language within last 10 years (1983-1992) were included in the review process. There has been no report of umbilical artery absent-end diastolic velocity before 1983. It was extremely difficult to draw a conclusion because a majority of the available reports in the literature are either case reports or retrospective analyses. However, for the practical purposes it can be concluded that after viability these pregnancies should be followed by intense (daily) fetal well-being surveillance with conventional antenatal tests. Those who improve their end-diastolic velocity should be allowed to continue the pregnancy as long as antenatal testing is promising. Persistence of absent end-diastolic velocity may be an indication for delivery at a gestational age when there is reasonable chance of survival. Cytogenetic evaluation and anatomical survey of these fetuses by ultrasound is recommended. Long-term follow up of surviving infants needs to be studied. It is impossible for a single institution to accumulate enough cases for adequate outcome evaluation. A randomized prospective trial to assess the management of pregnancies with absent end-diastolic velocity in the umbilical artery would be difficult. Some might even consider such a study unethical. Until such a study is performed, an international registry would be helpful for collecting data about the perinatal outcomes and management of such patients.

Assessment of the fetal PO2 changes by cerebral and umbilical Doppler on lamb fetuses during acute hypoxia

The objective of the present study was to validate one or a combination of fetal Doppler parameters in order to assess acute fetal hypoxia in an ovine model. Acute hypoxia was induced by reducing umbilical, or maternal aortic flow (approx. 70%). A CW Doppler probe was fixed on the fetal cervical skin, facing the internal carotid artery and the fetal abdominal skin adjacent to the umbilical arteries. (The angle between Doppler beam and flow vector remained constant.) A "Doptek 3000" spectrum analyser was used to measure the maximal and mean Doppler frequencies. Heart rate (HR), umbilical blood flow (UBF), carotid blood flow (CBF), umbilical RI (URI), cerebral RI (CRI) and cerebroplacental ratio (CPR = CRI/URI) were calculated in real time. A catheter was inserted into the fetal femoral artery, for blood gas (PO2, PCO2 pH) and blood pressure (BP) measurements. After 1 min of aorta compression (70% aortic flow reduction), the URI increased by 10% (P < 0.05), and the UBF decreased by 10% (P < 0.05), but the CRI decreased by 20% (P < 0.02), and the CBF did not change significantly. Fetal PO2 and CPR fell down after 1 min (59% and 38%, respectively; P < 0.001), although strong fetal heart rate decelerations were observed. The blood pressure, PCO2 and pH did not change significantly during this test. Throughout the 12 min of cord compression (70% umbilical flow reduction) the URI increased (70% to 80% P < 0.001), and the UBF decreased (approx. 60%; P < 0.001), but the CRI decreased (approx. 25%; P < 0.01), and the CBF remained constant (+/- 5%; ns). Fetal PO2 and CPR all decreased during the compression (30% to 44% and 40% to 60%, respectively; P < 0.001). HR, pH and PCO2 did not change significantly. During cord compression the blood pressure did not change significantly. In both cases, the CPR decreased significantly (P < 0.001) with the PO2 in the same direction and with a comparable amplitude (-30% to -50%). Nevertheless, the drop in CPR was greater during cord compression than during aorta compression, probably because the compression of the cord induced a central hypovolemia in addition to the hypoxia. The CPR was found to be the hemodynamic parameter that followed most closely the PO2 acute changes. The amplitude of the variations of this parameter (-30% to -50%) were quite similar to those of the PO2 during the period of acute hypoxia.(ABSTRACT TRUNCATED AT 400 WORDS)

Chromosomal abnormalities in fetuses with absent end-diastolic velocity in umbilical artery: analysis of risk factors for an abnormal karyotype

OBJECTIVE

Our purpose was to evaluate the incidence and patterns of chromosomal abnormalities in fetuses with absent end-diastolic velocity in umbilical artery and to analyze maternal and fetal factors associated with abnormal karyotype.

STUDY DESIGN

One hundred ninety-two fetuses of known karyotype with absent end-diastolic velocity in the umbilical artery at a gestational age > 20 weeks were considered. The following potential risk factors were analyzed in a multiple logistic regression model: maternal age, gravidity, parity, gestational age at diagnosis, presence of gestational hypertension and preeclampsia, presence of fetal malformations, different biometric measurements, head/abdominal circumference ratio, amniotic fluid volume, and several Doppler index values calculated from uterine arteries, fetal heart, and fetal peripheral arteries and veins.

RESULTS

Sixteen cases had an abnormal karyotype. In two cases a triploidy was present, whereas the remaining 14 cases had autosomal aberrations. The risk factors statistically significantly and independently associated with the presence of an abnormal karyotype were maternal age > 35 years, gestational age at diagnosis < 27 weeks, presence of multiple malformations, and absence of gestational hypertension and preeclampsia. All the fetuses with an abnormal karyotype but one were correctly identified by at least one risk factor.

CONCLUSIONS

An abnormal karyotype is present in 8.3% of fetuses with absent end-diastolic velocity in umbilical artery and is associated with maternal and fetal risk factors. The knowledge of these factors may be useful in the management of such fetuses.

Fetal cerebral and renal Doppler in small for gestational age fetuses in hypertensive pregnancies

The aim of the present work is to evaluate the hemodynamic disorders induced in several fetal vascular areas by maternal hypertension and to check the sensitivity and the specificity of the various Doppler parameters in the detection of small for gestational age (SGA) infants. The population consisted of 90 pregnant mothers aged 26.3 +/- 5.8 years with pregnancy-induced hypertension. Seventeen of them delivered moderate small for age babies (between the 10th and 5th centiles), without any neonatal complication. The opposition to flow in the fetal brain and kidney and in the placenta was evaluated using the Resistance Index (RI). The ratio of cerebral RI and umbilical RI, called the cerebroplacental ratio (CPR), was calculated and used as an indicator of fetal flow redistribution. The ability of CPR and renal RI to predict SGA at birth was evaluated; the sensitivity, specificity, positive predictive value, and negative predictive value for the CPR were 88.2%, 98.6%, 93.8% and 97.3%, respectively. The corresponding figures for the renal RI were 58.8%, 94.5%, 71.4% and 91%, respectively. Furthermore, in the SGA group, the abnormal renal RI values were both above and below the normal range, whereas the CPR values demonstrated consistent changes (always < 1).

CONCLUSION

this investigation demonstrates that in pregnancy-induced hypertension (even with moderate growth retardation, and no neonatal complication), the diagnostic efficacy of CPR for predicting SGA at birth is very high and that of renal RI correlates very poorly with fetal growth.